1. Field of the Invention
The present invention relates to: a piezoelectric actuator, including a column-like piezoelectric body and a driving power supply section, for moving a movable body by using mechanical vibration generated on a top face of the piezoelectric body; and a piezoelectric actuator array in which the piezoelectric actuators are arranged in a lattice pattern.
2. Description of Related Art
One of conventional piezoelectric actuators (hereinafter, referred to as a “first conventional device”) comprises a quadrangular column-like layered piezoelectric element. The first conventional device displaces a friction member contacting with a movable body (round body) by having the layered piezoelectric element undergo bending deformation and shear deformation, to thereby rotate the movable body owing to the displacement of the friction member. The first conventional device applies a voltage to the layered piezoelectric element in such a manner that a speed of the friction member when it is moving in a first direction is different from a speed of the friction member when it is moving in a second direction (refer to Japanese Patent Application Laid-Open No, 2006-238644).
However, according to the first conventional device, it is necessary to enlarge the bending deformation and the shear deformation in order to move the movable body rapidly, and thus, it is necessary to enlarge a height of the layered piezoelectric element. Consequently, it has a problem that a size of the piezoelectric actuator is large.
Another of the conventional piezoelectric actuators (hereinafter, referred to as a “second conventional device”) has a specific feature in an inner electrode of a column-like layered piezoelectric body. The second conventional device generates a bending vibration at an upper portion of the layered piezoelectric body, and simultaneously generates an expansion and contraction at a lower portion of the layered piezoelectric body, to thereby move the movable body by having a tip of the layered piezoelectric body move in an elliptical orbit (refer to Japanese Patent Application Laid-Open Hei No. 5-146171).
However, the second conventional device needs to have a driving circuit for applying to the layered piezoelectric element a driving voltage to cause the bending vibration, and another driving circuit for applying to the layered piezoelectric element another driving voltage to cause the expansion/contraction vibration, separately. Consequently, it has a problem that the number of the driving circuits becomes large.